//https://leetcode.cn/problems/flood-fill/

class Solution {
    int dx[4] = { 0,0,1,-1 };
    int dy[4] = { 1,-1,0,0 };
    int m, n;
    int prev;
public:
    vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int color)
    {
        if (image[sr][sc] == color) return image;

        m = image.size();
        n = image[0].size();
        prev = image[sr][sc];
        dfs(image, sr, sc, color);

        return image;

    }

    void dfs(vector<vector<int>>& image, int sr, int sc, int color)
    {
        image[sr][sc] = color;
        for (int k = 0; k < 4; k++)
        {
            int x = sr + dx[k];
            int y = sc + dy[k];
            if (x >= 0 && x < m && y >= 0 && y < n && image[x][y] == prev)
            {
                dfs(image, x, y, color);
            }
        }
    }
};